[Objectives]  Intraguild predation (IGP) plays a crucial role in regulating the abundance of predators of crop pests in agroecosystems. The conservation and utilization of important predators of rice planthoppers, the green mirid bug (Cyrtorhinus lividipennis Reuter) and the black mirid bug [Tytthus chinensis (Stål)] (Hemiptera: Miridae), could be improved by better understanding of IGP on these species in the rice ecosystem. [Methods]  A duplicate, species-specific, quantitative PCR for these two species was established to test and compare the magnitude of IGP by different predators in paddy fields planted with 2 rice varieties with different levels of resistance to rice planthoppers. [Results]  (1) The PCR had high specificity and similar sensitivity to both mirid species and could therefore be used to quantitatively measure the level of IGP. (2) Generalist predators collected from susceptible rice fields showed significantly higher levels of IGP on the green mirid bug compared to those from resistant rice fields. The level of predation on the green mirid bug was significantly different among different the generalist predator species tested, and was significantly higher than that on the black mirid bug. [Conclusion]  The relative magnitude of IGP on two mirids in rice fields can be related to host plant resistance to planthoppers, the species of generalist predators present, as well as prey species richness.